Combustion control system



April D. H. ANNIN 2,197,171

CQHBUSTION CONTROL SYSTEM Filed July 11, 1956 Ira/611101" Dough! 8 HATZTZ'LIL Patented Apr-.16, 1940 UNITED STATES PATENT OFFICE Douglas H.Annin, Chicago, Ill.,

assignor to Minneapolis Honeywell Regulator Company, Minneapolis, Minn,a corporation of Delaware Application July 11, 1936, Serial No. 90,149

9 Claims.

This invention relates to combustion control systems and an object ofthis invention is to provide a combustion control system of uniqueconstruction wherein the proportionate amounts of gas and air may besuitably adjusted to maintain desired combustion conditions, wherein therate of combustion may be automatically controlled in accordance withthe load on the boiler or manually controlled, wherein the supply of gasto the main burner is shut off when the draft through the boiler becomesdangerously low and wherein the supply of gas to the main burner atdangerously high pressures is prevented. I

The structure of the elements and the combination of the elements thatperform this mode of operation also form objects of this invention.

Other objects and advantages will become apparent to those skilled inthe art upon reference to the accompanying specification, claims anddrawing. a

For a more thorough understanding of this invention reference is made tothe accompanying single sheet of drawings, in which is diagrammaticallydisclosed the preferred form of my invention.

A boiler is generally designated at I9, and this boiler may includewater tubes I a steam header l2 and a water header l3. Steam may bedrawn from the steam header [2 through a suitable pipe I4 which leads toa point of use.

shown to be fired by a gas burner |5 which may be ignited by acontinually operating pilot burner Hi. The gases of combustion flow overthe water tubes through passe'sin the boiler formed by suitable baftlesl1 and I8. The gases of combustion are taken from the boiler H! by asuitable stack l9 and located in the stack I9 is a draft damper 20 whichis adapted to be moved to a plurality of positions to control the draftthrough the boiler Ill.

The draft damper 20 is adapted to be positioned by a floating motorgenerally designated at 22. This type of motor is old in the art andtherefore a complete description thereof is not 46 considered necessary.The floating motor 22 is controlled by a draft regulator generallydesignated at 23. This regulator 23 may be positioned in accordance withthe static pressure existing within the boiler ill or in accordance withthe 50 rate of flow of the gases of combustion through the boiler Ill.The supply of gas to the gas burner I5 is controlled by a diaphragm gasvalve generally designated at 24, and this diaphragm gas valve 24 isadjustably positioned by a pilot 55 regulator generally designated at25. The pilot The boiler is.

regulator 25 andthe static pressure regulator 23 are adjusted by aproportioning motor generally designated at 26. The proportioning motor25 may be of the type shown and described in Patent No. 1,989,972granted to Lewis L. Cun- 5 ningham on February 5, 1935. Theproportioning motor 26 may be positioned in any number of a plurality ofpositions by means of a pressure controller generally designated at 21or by a manual controller generally designated at 28. 10

A three-way solenoid valve generally desig-' nated at 29 is adapted toclose the diaphragm gas valve 24 to shut off the supply of gas to theburner l5 when the draft within the boiler 9 decreases to apredetermined value of when the 15 rate of flow of the gases ofcombustion through the boiler 40 decreases to a predetermined value.

A burner pressure safety controller generally designated at 30 controlsthe diaphragm gas valve 24 to prevent the gas pressure at the burner 20I5 from rising above a predetermined value.

A pipe 32 connecting into the diaphragm gas valve 24 conveys gas fromsome source, not shown, to the diaphragm gas valve 24. A pipe 33connects the diaphragm gas valve 24 to the 25 burner l5 to supply gas tothe burner l5 when the valve 34 of the diaphragm gas valve 24 is opened.The valve 34 is biased to a closed position by a compression spring 35and is connected by a rod 36 to a diaphragm 31 which forms an upperpressure chamber 38 and a lower pressure chamber The three-way solenoidvalve 29 may comprise valves 4| and 42 operated by a solenoid 43, thearrangement being such that when the solenoid 86 43 is deenergized thevalve 4! is open and the valve 42 is closed as shown in the drawing andwhen the solenoid 43 is energized the valve 4| is closed and the valve42 is open. The pilot regulator 25 may comprise a valve 45 operated by40 a diaphragm 4G. The valve 45 is biased towards an open position bymeans of a spring 41 which may be adjusted by means of a plunger 48.

Pipe 49 connects the gas supply pipe 32 to the pilot regulator 25 and.the pilot regulator 25 is 45 in turn connected by a pipe 59 to the upperportion of the three-way solenoid valve 29. The middle portion of thesolenoid valve 29 is connected by a pipe 5| to the pressure chamber 39of the diaphragm gas valve 24. The lower por- 50 tion of the three-waysolenoid valve 29' is connected by a pipe 52 to the pipe 53 whichsupplies gas to the pilot burner l6 from the gas supply line 32. Thepressure chamber 39 of the diaphragm gas valve 24 is also connected by apipe 54, an adjustable orifice 55 and a pipe 56 to the pipe 52. Thepressure chamber 38 of the diaphragm gas valve 24 is connected by a pipe51 to the pipe 33 which delivers gas to the main burner l5.

The burner pressure safety control device 30 may comprise a combineddiaphragm and valve 58 which is biased to a closed position by means ofan adjustable compression spring 59. Pipes and GI place this burnerpressure safety control device 30 in parallel with the adjustableorifice 55.

High pressure gas is delivered through the pipe 49 to the pilotregulator 25 and this pilot regulator 25 supplies gas at a constantpressure through the pipe 50, the three-way solenoid valve 29 and thepipe 5| to the pressure chamber 39 of the diaphragm gas valve 24. Thepressure at which gas is supplied to this pressure chamber 39 may beadjusted by varying the compression in the spring 41, the arrangementbeing such that as the plunger 48 is moved upwardly to increase thecompression in the spring 41 the pressure of the gas delivered to thepressure chamber 39 of the diaphragm gas valve 24 is increased. Gas isbled from the pressure chamber 39of the diaphragm gas valve 24 throughthe pipe 54, the adjustable orifice 55, pipes 55, 52 and 53 to the pilotburner l6, and for a given setting of the adjustable orifice 55 thebleeding action is maintained substantially constant. Therefore, thiscontrolled pressure in the pressure chamber 39 acts tolbias the valve 34towards an open position, the amount of biasing being dependent upon thepressure existing within the pressure chamber 39. Gas from thedownstream side of the diaphragm gas valve 24 is supplied to the upperpressure chamber 38 thereof, and by reason of this gas pressure existingwithin the upper chamber 38 a pressure regulating action is obtained.Due to the above construction, with a given position of the plunger 48of the pilot regulator 25, gas is supplied to the gas burner l5 at aconstant pressure and by moving the plunger 48 of the pilot regulator 25the pressure at which the gas is supplied to the main burner l5 may bead- J'usted.

Energization of the solenoid 43 closes the valve 4| and opens the valve42 of the three-way valve 29, which stops the supply of gas to the lowerpressure chamber 39 and connects this pressure chamber 39 through pipe5|, valve 42 and pipes 52 and 53 to the pilot burner l6 whereby thebiasing or valve opening action of the pressure chamber 39 isimmediately rendered ineffective and the valve 34 is closed by thespring 35. Threeway solenoid valve 29, therefore, acts as a safetydevice to cause closing of the valve 34 to stop the supply of gas to thegas burner I5 whenever the solenoid 43 is energized.

When the pressure in the pressure chamber 39 of the diaphragm gas valve24 rises above a predetermined value as determined by the compressionspring 59 of the burner pressure safety control device 39, the diaphragm58 thereof is moved upwardly to establish direct communication betweenthe pressure chamber 39 and the pilot burner l6 around the adjustableorifice 55. Therefore, when the pressure in the pressure chamber 39rises above a predetermined value the adjustable orifice 55 is shunted.to immediately relieve the pressure in the pressure chamber 39. Thisprevents the occurrence of undue pressures within the pressure chamber39 of the diaphragm gas valve 34 whereby gas at too high The staticpressure regulator 23 comprises an enclosed chamber having an invertedbell 63 suspended therein. The bell 63 is sealed by a suitable liquid todefine an upper chamber 64 and a lower chamber 65. If it be desired tooperate the regulator 23 in accordance with the static pressure orvacuum in the boiler I0, the lower pressure chamber 65 is connected by apipe 66 to a point adjacent the burner IS in the boiler I0. If it isdesired to operate the regulator 23 in accordance with the rate of flowof gases of combustion through the boiler Hi, the pipe 66 is extended toa point in the furnace adjacent the stack l9 and a pipe 61 leading fromthe upper pressure chamber 64 is adapted to extend to a point adjacentthe gas burner I5 in the boiler I0. The inverted bell 64 is suspended bya rod 68 which is in turn secured to a pivoted lever 69. The pivotedlever 69 is biased in one direction by means of a weight 10 and atension spring II. The weight 10 and the tension spring H tend to urgethe bell 63 upwardly. If the regulator 23 is used as a static pressureregulator the static pressure or vacuum in the boiler I 0 urges the bell63 downwardly against the action of the biasing means, the arrangementbeing such that as the static pressure decreases (as the vacuumincreases) the bell 63 is moved downwardly. As the static pressureincreases (as the vacuum decreases) the bell 63 is moved upwardly by thebiasing means 19 and II. If the regulator 23 is used as a rate of flowregulator, an increase in the rate of flow causes downward movement ofthe bell 63 against the action of the biasing means I0 and II and adecrease in the rate of flow allows upward movement of the bell 63 bythe biasing means 10 and H. The lever 69 operates a pivoted switchcarrier 12 which carries mercury switches 13 and 14. The arrangement issuch that as the bell 63 is moved downwardly in response to an increasein draft as caused by an increase in vacuum or as caused by an increasein the rate of flow of gases of combustion, the switch 13 is closed andwhen the bell 64 moves upwardly in response to a decrease in draft, theswitch 14 is closed. When the correct draft as determined by the correctvacuum or the correct rate of flow of gases of combustion is existingwithin the boiler ID, the mercury switches 13 and 14 are maintained inthe positions shown in the drawing, whereby the circuits therethroughare broken.

Power is supplied to the floating motor 22 by means of line wires 16 and11 leading from some source of power, not shown. The floating motor 22is connected by wires 18 and I9 to the mercury switches 14 and I3,respectively. The floating motor 22 is also connected by a wire 80 toboth of the mercury switches 12 and 13. The floating motor 22 is adaptedto operate the draft damper 20 through a crank 8| and a connecting rod82. When the draft in the boiler l0 increases, the mercury switch 13 ismoved to a closed position to complete a circuit for the floating motor22 through the switch 13 and the wires 19 and 80 to operate the floatingmotor 22 to move the draft damper 20 towards a closed position todecrease the draft in the boiler I0. A decrease in the draft in theboiler l0 causes movement of the mercury switch 14 to a circuit closingposition to complete a circuit therethrough and the wires [8 and 80 tooperate the floating motor 22 to move the damper 20 towards-an openposition to inlibrium will arise which maintains the mercury switches 13and 14 in circuit-breaking positions closed in the above Cunninghampatent.

whereby the draft damper 20 is positioned to maintain the desired draftin the boiler I0. The values of the vacuum or the values of the rate offlow of the gases of combustion in the boiler I0 may be adjusted byvarying the tension in the biasing spring 1|. Specifically, increasingthe tension in the biasing spring 1| increases the value of the vacuumor the value of the rate of flow of the gases of combustion in theboiler I0. Vice versa, decreasing the tension in the biasing spring 1Idecreases the values of the vacuum or the rate of flow of the gases ofcombustion in the boiler I0.

Line wires leading from some source of power, not shown, are designatedat 84 and 85. The primary 86 of a step-down transformer 81 having asecondary 88 is connected across the line wires 84 and 85. The secondary8B is connected by wires 89 and 90 to the proportioning motor 26 tosupply electrical energy thereto. The proportioning motor 26 positionsthrough suitable gearing 9| a rotatable shaft 92 which carries discs'94and 95. The discs 94 and 95 are provided with a plurality of adjustablescrews 96 and 91, respectively. The adjustable screws 96 and 91 provideadjustable cams in the manner shown in the drawing. The adjustablescrews 96 operate a roller 98 carried by a pivoted lever 99 to which isconnected by a suitable nut and screw arrangement I00 the biasing spring1I. Rotation of the shaft 92, therefore, causes adjustment of thebiasing spring 1|. The adjustable screws 91 operate a follower in theform of a roller IOI which is carried by a pivoted lever I02 which inturn abuts the plunger 48 of the pilot regulator 25. Rotation,therefore, of the shaft 92 causes movement of the plunger 48 of thepilot regulator 25 to adjust the gas pressures being delivered to themain burner I5.

The pressure regulator generally designated at 21 may comprise apressure bellows I04 connected by a pipe I05 to the steam pipe I4 andthis bellows I04 is adapted to operate a slider I06 with respect to apotentiometer coil I01. The arrangement is such that as the pressureincreases the slider I06 is moved upwardly with respect to thepotentiometer coil I01 and as the pressure decreases the slider I06 ismoved downwardly. The ends of the potentiometer coil I01 are connectedby wires I08 and I09 to the proportioning motor 26. The manualcontroller generally designated at 28 comprises a contact IIO, a sliderIII operated by a suitable knob H2 and a potentiometer coil H3. Theslider III is adapted to engage the contact H0 or the potentiometer coilI I3. The ends of the potentiometer coil II3 are connected by wires H4and H5 to the wires I08 and I09 leading to the'proportioning motor 26.The slider I06 of the pressure controller 21 is connected by a wire II6to the contact IIO of the manual controller 28 and the slider IIIthereof is connected by a wire 1 to the proportioning motor 26.

With the manual controller 28 in the position shown in the drawing, thepotentiometer operated by the pressure controller 21 is connected to theproportioning motor 26 in the manner dis- Upon an increase in pressure,the proportioning motor 261s positioned in accordance with this increaseto proportionately position the shaft82 to decrease the tension in thespring H and decrease the compression in the spring 41 of the pilotregulator 25. This causes a decrease in the pressure of the gas beingdelivered to the gas burner I5 and a decrease in vacuum or rate of flowof the gases of combustion through the boiler I0. This allows the steampressure to decrease to the desired value. When the steam pressuredecreases, the slider I06 is moved downwardly with respect to thepotentiometer coil I01 to operate the proportioning motor 26, whichproportionately positions the shaft 92 in such a manner as to increasethe tension in the spring II and increase the compression in the spring41, the amount of increase in this tension and compression of thesprings H and 41 being proportionate to the amount that the steampressure lowers from the desired value. Increasing of the tension in thespring H in this manner increases the vacuum or the rate of flow ofgases of combustion in the boiler I0 and increasing of the compressionof the spring 41 proportionately increases the gas pressure of the gasbeing delivered to the gas burner I5. This increase in gas pressure andthis increase in rate of flow of the gases through the boiler I0 raisesthe steam pressure to the desired value.

Movement of the slider III of the manual controller from the contact IIOinto engagement with the potentiometer coil II 3, breaks the connectionbetween the slider I06 of the pressure controller 21 and theproportioning motor 26 thereby rendering the pressure controller 21inoperative to control the proportioning motor 26. This also places theproportioning motor under the control of the manual controller 28 andmovement of the slider III with respect to the potentiometer coil II3causes operation of the proportioning motor 26 in the same manner asdoes movement of the slider I06 with respect to the potentiometer coilI01 of the pressure controller 21. In this manner, automatic control ofthe proportioning motor 26 is prevented and the proportioning motor 26may be positioned manually.

The pivoted lever 69 of the draft regulator 23 is also adapted tooperate a mercury switch I20 which is carried by a pivoted lever I2I.The pivoted lever I2I also carries an adjustable screw I22 which isadapted to be engaged by the pivoted lever 69. The arrangement is suchthat when the vacuum decreases to a given value or when the rate of flowof the gases of combustion through the boiler I0 decreases to apredetermined value, the mercury switch I 20 is tilted to acircuit-making position. This causes completion of a circuit from thesecondary 88 through wire I23, mercury switch I20, wire I 24, solenoid43 and wire I25 back to the secondary 88. Completion of this circuitcauses energization of the solenoid 43 to operate the three-way valve 29to decrease the pressure in the pressure chamber 39 of the diaphragm gasvalve 24 to stop the supply of gas to the main gas burner I5. Thereforewhenever the draft through the boiler I0 becomes dangerously low, thesupply of gas to the gas burner I5 is shut off. 7

By suitably adjusting the screws 96 and 91 forming the adjustable earns,the gas and air supplied to the boiler I0 may be proportioned withrespect to each other so as to maintain a desired CO2 content in thegases of combustion.

From the above it is seen that I have provided a combustion controlsystem of unique construction wherein the proportionate amounts oi gasand air may be suitably adjusted to maintain desired combustionconditions, wherein the rate of combustion may be automaticallycontrolled in accordance with the load on the boiler or manuallycontrolled, wherein the supply of gas to the main burner isshut off whenthe draft through the boiler becomes dangerously low and wherein thesupply of gas to the main burner at dangerously high pressure values isprevented.

Although I have shown for purposes of illustration one form of myinvention, my invention is not to be limited thereby but is to belimited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a combustion control system, the com-' bination of a furnacehaving fuel supplying means and draft regulating meansan adjustablecontroller responsive to the rate of fuel supply in control of said fuelsupplying means, an adjustable controller responsive to the draft in thefurnace in control of said draft regulating means, said controllersbeing adjusted with respect to each other for maintaining desired ratiosof fuel supply and draft, automatic means responsive to a condition forsimultaneously adjusting both controllers to increase or decrease therate of combustion, said automatic means comprising cam means wherebysaid ratios can be maintained at desired values over a wide range ofvalues of said condition.

2. In a combustion control system, the combination of a furnace havingfuel supplying means and draft regulating means, an adjustablecontroller responsive to the rate of fuel supply in control of said fuelsupplying means, an adjustable controller responsive to the draft in thefurnace in control of said draft regulating means, said controllersbeing adjusted with respect to each other for maintaining desired ratiosof fuel supply and draft, automatic means responsive to a condition forsimultaneously adjusting both controllers to increase or decrease therate of combustion, said automatic means comprising a cam and a manualadjustment therefor, said means being manually adjustable whileautomatically adjusting said controllers .and manually operated meanscomprising a switch for rendering said automatic means inoperative andfor manually controlling both controllers.

3. In a combustion control system, the combination of a furnace havingfuel supplying means comprising an adjustable pressure regulator anddraft regulating means, an adjustable controller responsive to the rateof fuel supply in control of said fuel supplying means, an adjustablecontroller responsive to the draft in the furnace in control of saiddraft regulating means, said controllers being adjusted with respect toeach other for maintaining desired ratios of fuel supply and draft,automatic means responsive to a condition for simultaneously adjustingboth controllers to increase or decrease the rate of combustion, meansoperative to move said pressure regulator in closing direction forpreventing the supply of an excess quantity of fuel, and meansresponsive to a decrease in draft for stopping the supply of fuel tosaid furnace by closing said pressure regulator.

4. In a combustion control system, the combination of a furnace havingfuel supplyingmeans and draft regulating means, an adjustable controllerin control of said fuel supplying means, an adjustable controller incontrol of saiddraft regulating means, said controllers being adjustedwith respect to each other for maintaining desired ratios of fuel supplyand draft, manually adjustable cam means for adjusting said firstmentioned controller, manually adjustable cam means for adjusting saidsecond mentioned controller, and automatic means responsive to acondition for operating said cam means whereby said manually adjustablecontrollers are adjusted to increase or decrease the rate of combustion,said manually adjustable cam means providing adjustments wherebyresponses transmitted by said cam means when operated by said conditionresponsive means can be varied.

5. In a combustion control system, the combination of a furnace havingfuel supplying means and draft regulating means, an adjustableeontroller in control of said fuel supplying means, an adjustablecontroller in control of said draft regulating means, said controllersbeing adjusted with respect to each other for maintaining desired ratiosof fuel supply and draft, an adjustable cam means for adjusting saidfirst mentioned controller, an adjustable cam means for adjusting saidsecond mentioned controller, automatic means responsive to a conditionfor operating said cam means whereby said controllers are adjusted toincrease or decrease the rate of combustion in accordance with changesin the condition by proportionately varying the draft and the supply offuel, means for preventing the supply of an excess quantity of fuel, andmeans responsive to a decrease in draft for stopping the supply of fuelto said furnace.

6. In a combustion control system, the combination of a furnace having aburner for gaseous fuel and a draft damper, an adjustable pressureregulator in control of the supply of fuel to said burner, power meansfor operating said draft damper, an adjustable pressure responsivecontroller in control of said power means, control means for adjustingsaid pressure regulator and said pressure responsive controller,automatic means responsive to changes in a condition for controllingsaid control means whereby the rate of combustion is varied inaccordance with changes in the condition by proportionately varying thedraft and the supply of fuel, and means for moving said pressureregulator to a closed position when the draft decreases to apredetermined value.

'7. In a combustion control system, the combination of a furnace havinga burner for gaseous fuel and a draft damper, an adjustable pressureregulator in control of the supply of fuel to said burner, power meansfor operating said draft damper, an adjustable pressure responsivecontroller in control of said power means, control means for adjustingsaid pressure regulator and said pressure responsive controller,automatic means responsive to changes in a condition for controllingsaid control means whereby the rate of combustion is varied inaccordance with changes in the condition by proportionately varying thedraft and the supply of fuel, means for moving said pressure regulatorto a. closed position when the draft decreases to a predetermined value,and means for preventing the pressure of the gaseous fuel at the burnerfrom exceeding a predetermined value.

8. In a combustion control system, the combination of a furnace having aburner for gaseous fuel and a draft damper, an adjustable pressureregulator in control of the supply of fuel to said burner, power meansfor operating said draft damper, an adjustable pressure controller incontrol of said power means, manually adjustable cam means for adjustingsaid pressure regulator, an adjustable cam means for adjusting saidpressure controller, and means responsive to changes in a condition forsimultaneously operating said manually adjustable cam means whereby therate of combustion is varied in accordance with changes in the conditionby proportionately varying the draft and the supply of fuel, saidmanually adjustable cam means providing adjustments whereby theoperative relationship between said condition responsive means and saidpressure regulator and said power means can be varied.

9. In a combustion control system, the combination of a furnace having aburner for gaseous fuel and a draft damper, an adjustable pressureregulator in control of the supply of fuel to said burner, power meansfor operating said draft damper, an adjustable pressure controller incontrol of said power means, an adjustable cam means for adjusting saidpressure regulator, an adjustable cam means for adjusting said pressurecontroller, means responsive to changes in a condition forsimultaneously operating said cam means whereby the rate of combustionis varied in accordance with changes in the condition by proportionatelyvarying the draft and the supply of fuel, means for moving said pressureregulator to a closed position when the draft decreases to apredetermined value, and means for preventing the pressure of thegaseous fuel delivered to the burner from exceeding a predeterminedvalue.

DOUGLAS H. mm.

CERTIFICATE OF CORRECTION.

Patent No. 2,197,171. April 16, 191 0 DOUGLAS H. ANNIN. I

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1.1.,second column, line 8, claim 11, strike out the words "manuallyadjustable" and insert the .same before "cam means" in line 7, sameclaim; and that the said Letters Patent should be read with thiscorrection therein that the same may conform ,to the record of the casein the Patent Office.

Signed and sealed this 2nd day of July, A. D. 191 0.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

